Heretofore, TiC has been known to be a high temperature material having excellent anti-spalling property, because of its high melting point and high hardness, of its low thermal expansion, and of its sustained heat-conductivity even at high temperatures. In view, however, of the fact that TiC is a material difficult to be sintered, it has been a general practice to use the material in the form of a cermet which is obtained by adding to TiC various metals such as Co, Ni and so forth, so as to be sintered in high density, although the addition of such metals has a disadvantage of deteriorating heat-resistance of the material.
For example, in the cutting of ductile cast iron, a cermet tip (or insert) utilizing the abovementioned cermet is employed for the finishing cut. Even such finishing cut, however, would bring about rapid wear at such high cutting speed that exceeds 300 m/min., cause cratered wear, and further tend to readily form chipping. At a cutting speed ranging from 150 to 200 m/min., or slower than that, fusion-adhesion takes place, if not to a degree for tips of super-hard (cemented) materials, to unavoidably roughen the finished surface of the work as cut.
The present inventors have previously proposed a TiC-based ceramic material which, by rendering a metal to assume a state of solid-solution in TiC, is made excellent in the heat-resistance and prevents detrimental effect caused by the metal component at a high temperature (vide: Japanese Patent Kokai Publication No. 61-26564 and Japanese Patent Application No. 60-173519 now JP-Patent-Kokai Publication No. 62-36065).
However, the abovementioned TiC-based ceramic material is inferior to cermet in respect of its toughness, hence the range of its utility has been limited.
Techniques of including the whiskers in the ceramics have generally been disclosed in Japanese Patent Kokai Publication No. 59-102861 (for the purpose of imparting high electric conductivity), and in U.S. Pat. No. 4,543,345 (for the purpose of imparting toughness). JP Kokai No. 59-102861 discloses oxide ceramics such as Al.sub.2 O.sub.3, ZrO.sub.2, MgO as the matrix, while U.S. Pat. No. 4,543,345 discloses matrix of Al.sub.2 O.sub.3, mullite or B.sub.4 C. However, these techniques do not provide sufficient compatibility and bonding force between SiC whisker and the matrix.
Thus there has been much to be desired in the art to provide a still improved ceramic-base/SiC whisker composite ceramic body, particularly suitable for cutting tools.